Definition from buildingSMART: This objectified
relationship IfcRelAssignsToProduct handles
the
assignment of objects (subtypes of IfcObject) to a
product (subtypes of IfcProduct).

The Name attribute should be used to
classify the usage of the IfcRelAssignsToProduct
objectified relationship. The following Name values
are proposed:

'Reference' : Assignment of a
product (via RelatingProduct)
to a spatial structure (via RelatedObjects) to
which it is referenced (in contrary to being contained - which is
handled by IfcRelContainedInSpatialStructure).

IFC2x
Edition 3 CHANGE The reference of a product within a spatial
structure is now handled by a new relationship object
IfcRelReferencedInSpatialStructure. The IfcRelAssignsToProduct
shall not be used to represent this relation from
IFC2x3 onwards.

'Context' : Assignment of a
context specific
representation, such as of structural members to a different context
representation (with potentially different decomposition breakdown)
such as of building elements for a specific context
specific representation.

IFC2x
Edition 3 CHANGE The relation of a structural member (as
instance of IfcStructuralMember or its subclasses)
to a physical element (as instance of IfcElement
or its subclasses) is now handled by a new relationship
object IfcRelConnectsStructuralElement. The IfcRelAssignsToProduct
shall not be used to represent this relation from
IFC2x3 onwards.

'View' : Assignment of a product (via RelatingProduct)
that is decomposed according to a discipline view, to another product
(via RelatedObjects) that is decomposed according
to a different discipline view. An example is the assignment of the
architectural slab to a different decomposition of the pre manufactured
sections of a slab (under a precast concrete discipline view).